My pillow is my fleece, wrapped in a towel. Works great. Doesn't weigh anything, because I'm already taking the fleece for warmth, and the little towel as well.

And I agree about the little pad of blue foam for a seat. We call them our "camp chairs." One goes on the outside of each our packs, so that we can even use them quickly and easily on a quick break along the trail. Also good for protecting knees while you are cooking, entering the tent, etc.
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Or just read a good mystery novel set in the Sierra;